Chain with opposite plane links

ABSTRACT

A chain with opposite plane links is disclosed and may be utilized in connection with an excavator or other heavy-duty operation. Each opposite plane link includes two discrete loop portions orthogonally-oriented with respect to each other. The excavator may be, for example, a dragline excavating operation that includes a drag rope and a dragline bucket. The opposite plane link chain forms a portion of the drag system positioned adjacent to the dragline bucket and secured to the dragline bucket. In operation, the opposite plane link chain drags against the ground and experiences wear. By rotating the opposite plane link chain and reversing the ends of the opposite plane link chain, four discrete wear surfaces are sequentially positioned to engage the ground.

CROSS-REFERENCE To RELATED APPLICATION

[0001] This application claims priority to a U.S. Provisional Patent Application, which was filed in the U.S. Patent and Trademark Office on Jun. 3, 2002 and accorded Serial No. 60/384,420.

FIELD OF THE INVENTION

[0002] The present invention relates to a chain with opposite plane links and has application, for example, to mining equipment utilized in a dragline excavating operation.

BACKGROUND AND SUMMARY OF THE INVENTION

[0003] In a mining operation that includes a dragline bucket, excavation is accomplished by supporting and dragging the dragline bucket along the ground through the use of drag chains and drag ropes (e.g., cables). Examples of such mining operations, which are referred to herein as dragline excavating operations, are disclosed in U.S. Pat. No. 4,791,738 and U.S. Pat. No. 5,084,990 to Briscoe. A pair of drag chains are secured to a front of the dragline bucket to connect the dragline bucket to one or more pulling drag ropes that are operated (i.e., lengthened or shortened) by a drag mechanism. As the dragline bucket is pulled across the ground, these drag chains also engage the ground in the excavation area. The drag chains, therefore, experience significant wear as various links of the drag chains slide against the ground. A conventional chain for a dragline excavating operation includes a plurality of links with a generally flat and oval configuration. Other chains proposed for use in dragline excavating operations are disclosed in U.S. Pat. No. 4,060,978 to McBain et al.; U.S. Pat. No. 6,170,248 to lanello et al.; and U.S. Pat. No. 3,181,257 to Larsen.

[0004] In accordance with the present invention, a chain for a dragline excavating operation incorporates opposite plane links that are each formed with first and second discrete loops angled with respect to each other. In a preferred construction, the loops of each link are orthogonal to one another. The opposite plane links have a robust, strong construction and are preferably formed as one-piece, rigid parts. The loops form apertures that are preferably oriented orthogonally with respect to each other. Loops of adjacent links extend through the apertures to interconnect a plurality of links and form the chain. In addition to the loops, each link also includes a connector portion that extends between the loops and is formed integral with the loops. By using a single connector portion between the loops, the length of each link can be increased. For example, the pitch dimension of each link can be twelve times the cross-sectional dimension of the link or more. The use of such a single rod of metal as the connector portion, which constitutes the majority of the length of each link, results in a considerable weight savings as opposed to the conventional links where opposite ends of each link are connected by a pair of metal rod portions.

[0005] While chains with opposite plane links are not new per se, they have not been previously used in connection with a dragline excavating operation or other similar excavation operation within an abrasive environment. Rather, such chains have found use in the making of jewelry and other relatively light duty operations. See, for example, U.S. Pat. No. 507,346 to Atwood and U.S. Pat. No. 2,807,929 to Gantz. As can be appreciated, these chains lack a construction that could withstand the rigors encountered in a dragline excavating operation. Furthermore, such chains have not had a connector portion between the loops which increases the overall length of each link and, by extension, decreases the total weight of the strand of chain.

[0006] The use of the inventive opposite plane chain in a dragline excavating operation provides a number of advantages that are unknown in the prior art. These advantages include the following: (1) The chain can be rotated four times for wear because, regardless of the quantity of links, the end links are always in opposite plane; (2) The center portion of each link is in the wear shadow, therefore this section is lighter as it does not have to contain wear metal for a high factor of safety; (3) Each link changes the plane of the chain, therefore flexibility of the chain is increased as each link acts as a double swivel;

[0007] (4) Better strength to weight ratio than flat and oval link chain; (5) High wear metal in the bight area; and (6) Lighter weight per foot than flat and oval link chain.

[0008] The advantages and features of novelty characterizing the present invention are pointed out with particularity in the appended claims. To gain an improved understanding of the advantages and features of novelty, however, reference may be made to the following descriptive matter and accompanying drawings that describe and illustrate various embodiments and concepts related to the invention.

DESCRIPTION OF THE DRAWINGS

[0009] The foregoing summary, as well as the following Detailed Description of the Invention will be better understood when read in conjunction with the accompanying drawings.

[0010]FIG. 1 is a perspective view of a dragline bucket and rigging that incorporates a chain with opposite plane links in accordance with the present invention.

[0011]FIG. 2 is a top plan view of a portion of the chain with opposite plane links.

[0012]FIG. 3 is a side elevational view of the portion of the chain with opposite plane links.

[0013]FIG. 4 is a perspective view of the portion of the chain with opposite plane links.

[0014]FIG. 5 is a side elevational view of another portion of the chain with an opposite plane link and a conventional link to illustrate a difference in pitch length between the two types of links.

[0015]FIG. 6 is a fragmentary view of the chain with opposite plane links depicting another system for securing the chain with opposite plane links to a dragline bucket.

DETAILED DESCRIPTION OF THE INVENTION

[0016] A dragline excavating operation may have a variety of different constructions. As an example, a dragline excavating operation may include a housing, a boom, a hoist rope, a dragline bucket, and a drag rope. The hoist rope is controlled by a hoist winch. Similarly, the drag rope is controlled by a drag winch, which is utilized to decrease the effective length of the drag rope, thereby pulling the dragline bucket across an excavation area and filling the dragline bucket with earthen material to be removed from the excavation area. The present invention is a chain in the dragline excavating operation that has opposite plane links. The present invention is not limited to this specific kind of system, however, and the present invention can be used as the chain for nearly any type of dragline excavating operation.

[0017] An example of a dragline bucket 50 and rigging that includes a drag system 60 is depicted in FIG. 1. Dragline bucket 50 has a pair of spaced vertical sides 52 and a rear wall 53 that extend upward from a bottom surface 54 to form a generally scoop-shaped structure for receiving the earthen material. A front end 55 of dragline bucket 50 is open, and bottom surface 54 defines a horizontal digging edge or lip to which a plurality of excavating teeth 56 are attached.

[0018] A drag system 60 is secured to dragline bucket 50 and includes a pair of drag ropes 62 (e.g., cables) and a pair of drag chains 64, although other arrangements can be used. A pair of connectors 58 extend forward from sides 52 to provide sites for securing drag chains 64 to dragline bucket 50. A first end of each drag rope 62 is secured to the drag winch, and a second end of each drag rope 62 is secured to one of drag chains 64 at a connection site 66. Similarly, a first end of each drag chain 64 is secured at connection site 66, and a second end of each drag chain 64 is secured to one of connectors 58 on dragline bucket 50. That is, the forward sides of dragline bucket 50 are equipped with shackles, which have generally vertical pins 59, to which drag chains 64 attach. As an alternate structure, a generally horizontal pin 59 a is depicted in FIG. 6.

[0019] Drag chains 64 are composed of a plurality of interconnected, preferably identical opposite plane links. A portion of one preferred construction of drag chains 64 is depicted in FIGS. 2-4. Drag chains 64 each include a plurality of interconnected links 70 that each have a first loop portion 72, a second loop portion 74, and a connector portion 76 positioned therebetween. Each first loop portion 72 and second loop portion 74 are generally circular or round in shape and define an aperture, but could have other shapes. Connector portion 76 is integrally-formed with each of first loop portion 72 and second loop portion 74, and connector portion 76 extends between each of first loop portion 72 and second loop portion 74. Accordingly, each link 70 includes two loop portions 72 and 74 that form apertures oriented orthogonally with respect to each other. Each first loop portion 72 extends through the aperture formed by a second loop portion 74 of an adjacent link 70. Similarly, each second loop portion 74 extends through the aperture formed by a first loop portion 72 of another adjacent link 70. In this manner, the various links 70 are interconnected to form drag chains 64. Each link 70 may be formed through a casting or forging process such that first loop portion 72, second loop portion 74, and connector portion 76 are one-piece members that are integrally-connected with each other to form a rigid, one-piece structure for each link 70.

[0020] As depicted in the alternate configuration of FIG. 6, one of links 70 may be directly secured to a connector 58 a. Since links 70 each include loop portions 72 and 74 in different orthogonally related planes, drag chain 64 can be attached directly to connector 58 a and pin 59 a to avoid the mounting rings or pear links that are used in conventional systems to ensure that the conventional chains can always be secured to the shackles irrespective of the orientation of the final link. This elimination of a part also provides weight reduction to the system. As can be appreciated, each link 70 is substantially identical to eliminate the need for the special end loop of the prior art. Instead, a bushing can be provided in the usual opening. Similar considerations apply to connector 58 and other connection systems.

[0021] In a conventional chain for dragline excavating operations, each link has a generally planar configuration. More specifically, the aperture or apertures that receive portions of adjacent links are on a single plane. With reference to U.S. Pat. No. 4,060,978 to McBain et al., for example, each link forms two apertures for receiving portions of adjacent links, and the apertures are located on a single plane. In each link 70, however, the aperture formed by first loop portion 72 is oriented at approximately 90 degrees with respect to the aperture formed by second loop portion 74. Therefore, the planes of the apertures formed by first loop portion 72 and second loop portion 74 are substantially orthogonal to each other. Although the orientation of the apertures preferably 90 degrees to each other, an orientation in the range of 60 degrees to 120 degrees, for example, may also be utilized in one or more links 70.

[0022] According to conventional thinking, in the conventional chain that has the generally flat and oval link configuration, the pitch (i.e., the distance from the inside surface at one rounded end portion to the inside surface at the opposite rounded end portion of the same link) of each link is approximately four times the cross-sectional dimension (i.e., the thickness of one of the two rods forming sides of the conventional chain) to provide adequate strength. As an example, then, a link with a four inch cross-section will generally have a sixteen inch pitch. In many circumstances, tensile forces tend to elongate the link and draw sides of the link together, thereby deforming the link to have the general shape of a figure eight. In order to resist the deformation, some links may incorporate a brace that extends between opposite sides of the link, as in the McBain et al. patent discussed above, which further adds to the weight of each link. The tendency for the sides to draw together increases as the pitch of the link increases in proportion to the cross-section. For this reason, the pitch of many links with an oval configuration is approximately limited to four times the cross-section. FIG. 5 depicts one of links 70 in combination with a generally conventional link 80 to illustrate a difference in pitch length between the two types of links.

[0023] In contrast to the conventional chains utilized in dragline excavating operations, links 70 of the present invention may be proportioned such that the pitch (i.e., the distance from the inside surface at the end of first loop portion 72 to the inside surface at the end of second loop portion 74 of the same link 70) is most preferably approximately eight times the cross-section or nominal diameter (i.e., the thickness of link 70 at connector portion 76) of the chain. Accordingly, a link 70 that has a cross-section of four inches may have a corresponding pitch of 32 inches, for example. Within the scope of the present invention, however, the pitch may preferably range from four to twelve times the cross section, but may have other relationships as well. The use of orthogonal loops with a single connector rod does not suffer the same failings as the conventional links described above.

[0024] The increased pitch to cross-section ratio discussed above reduces the total number of links 70 that are utilized to form a given length of each drag chain 64. Moreover, by using a connector portion 76 that is formed as a single rod, instead of as two rods in a conventional link, (1) the connector portion 76 may exhibit a much smaller diameter than the sum of the two rod portions of the conventional link; (2) a lesser amount of material is utilized to form a given length of each drag chain 64; and (3) the overall weight of each drag chain 64 is decreased. In comparing one conventional chain for dragline excavating operations with a drag chain 64 in accordance with the present invention that would be designed for the same systems, drag chains 64 may be lighter and yet provide comparable tensile strength and wear-resistance. Advantageously, the lesser weight permits links 70 to be formed with greater dimensions, thereby further increasing tensile strength or wear-resistance, and/or dragline bucket 50 may have an increased size. When drag chains 64 are sold with a dragline bucket 50, then the capacity of dragline bucket 50 can be increased to take advantage of the reduced weight of drag chains 64. This increased capacity provides increased productivity and decreased cost to the dragline excavating operation. Alternately, drag chains 64 can be made more robust to provide longer wear life and less down time to the dragline excavating operation, which also provides a reduction in overall cost.

[0025] As discussed above, drag chains 64 may be lighter and yet provide comparable tensile strength and wear-resistance. As an example, the weight of the link in a conventional chain for dragline excavating operations that has a 4 inch cross-section may be approximately 239 pounds, whereas the weight of link 70 having similar cross-sectional dimensions is 352 pounds. Two links of the conventional chain have a length that is comparable to the pitch of link 70. Accordingly, two links of the conventional chain weigh 36% more than one link 70. Drag chains 64 provide, therefore, significant weight savings in comparison to a similar length of the conventional chain. Greater or lesser weight savings may be realized in other systems with shorter or longer links. Moreover, weight reduction benefits a dragline excavating operation because the boom is constructed to excavate and haul a certain total weight including the weight of the dragline bucket, rigging, and load (i.e., the excavated material). A reduction in the weight of the chains, such as drag chains 64, increases the amount of load that can be gathered with each pass of the dragline bucket.

[0026] In pulling dragline bucket 50 across the excavation area, links 70 of drag chains 64 will often slide along the ground. Following repeated use, therefore, many of links 70 wear in areas that contact the ground. In contrast with links of conventional chains for dragline excavating operations with flat and oval links, which have only two wear surfaces, each link 70 has four discrete wear surfaces that include: a first wear surface 78 a positioned on a side of first loop portion 72; a second wear surface 78 b positioned on an opposite side of first loop portion 72; a third wear surface 78 c positioned on a side of second loop portion 74; and a fourth wear surface 78 d positioned on an opposite side of second loop portion 74.

[0027] Drag chains 64 may be utilized such that each wear surface 78 a-78 d sequentially experiences wear during operation of the dragline excavating operation. In other words, each drag chain 64 may be incorporated into the dragline excavating operation such that first wear surface 78 a initially contacts the ground and slides against the ground as dragline bucket 50 repeatedly gathers a load of earthen material. Once first wear surface 78 a experiences a relatively high degree of wear, the manner in which each drag chain 64 is secured to dragline bucket 50 and drag ropes 62 may be modified such that second wear surface 78 b contacts the ground and slides against the ground as dragline bucket 50 repeatedly receives earthen material. Thereafter, third wear surface 78 c and fourth wear surface 78 d are subsequently placed into position to contact the ground and experience wear.

[0028] Drag chains 64 may be initially secured to dragline bucket 50 such that, for example, first wear surfaces 78 a of links 70 face downward toward the ground. Following repeated use of the dragline excavating operation, drag chains 64 may be inspected to determine the amount of wear experienced by first wear surfaces 78 a. Once a threshold amount of wear has occurred (i.e., after first wear surfaces 78 a become worn from engaging the ground), drag chains 64 may be disconnected from dragline bucket 50 and drag ropes 62 and rotated 180 degrees about a length thereof. In other words, drag chains 64 may be rotated such that second wear surfaces 78 b of links 70 face downward toward the ground. Following further use of the dragline excavating operation, drag chains 64 may be inspected once again to determine the amount of wear experienced by second wear surfaces 78 b. Once the threshold amount of wear has occurred, drag chains 64 may be again disconnected from dragline bucket 50 and drag ropes 62. Rather than merely rotate drag chains 64 about the length, drag chains 64 are rotated end over end such that the ends that were secured to drag ropes 62 are now secured to dragline bucket 50. In this way, the other links can be oriented to attach to dragline bucket 50.

[0029] By reversing the positions of the ends of drag chains 64 with respect to drag ropes 62 and dragline bucket 50, drag chains 64 may be reconnected to dragline bucket 50 and drag ropes 62 such that third wear surfaces 78 c of links 70 face downward toward the ground and the general process described above may be repeated. That is, drag chains 64 may be disconnected from dragline bucket 50 and drag ropes 62 and rotated 180 degrees about the length thereof once third wear surfaces 78 c wear beyond the threshold amount, thereby positioning fourth wear surfaces 78 d to face downward toward the ground. Once the threshold amount of wear occurs on fourth wear surfaces 78 d, drag chains 64 may be recycled. Alternately, specific links 70 that are particularly worn may be replaced or reinforced such that drag chains 64 may be utilized again.

[0030] While a conventional chain for dragline excavating operations also has four different wear surfaces (i.e., two on each pair of adjacent links) each link does not include four different wear surfaces. Further, since the elongated center connector portion 76 of the present invention is recessed relative to the outer loops, it typically does not engage the ground and experience the same level of wearing. As a result, connector portion 76 need not be as thick as the side portions of a conventional chain because it does not slide against the abrasive ground surface. Moreover, the contact surface is less in the inventive drag chain 64 to reduce the frictional drag loads caused by drag chains 64.

[0031] As discussed above, a conventional chain also has four different wear surfaces, but each link does not include four different wear surfaces, as in drag chains 64. The ability to utilize the conventional chain in a manner that places each of the four wear surfaces in contact with the ground depends primarily upon the number of links in the conventional chain. If the conventional chain has an odd number of links, then reversing the conventional chain end over end will not change the wear surfaces that contact the ground, whereas forming the conventional chain with an even number of links permits a change in the wear surfaces. In drag chains 64, however, the wear surfaces may be changed regardless of the number of links in drag chains 64.

[0032] Drag chains 64 are disclosed above as being incorporated into drag system 60. Chains having the configuration of drag chains 64 may, however, find application in other portions of the dragline excavating operation. For example, FIG. 1 depicts conventional flat, oval link chains as supporting dragline bucket 50. A chain having the configuration of drag chains 64 may also be utilized to support dragline bucket 50. In addition, a chain having the configuration of drag chains 64 may be utilized in other types of heavy-duty operations. For example, an opposite plane link chain may be utilized as a chain for mooring ships or as a chain in a conveying operation. Accordingly, a chain having opposite plane links may be utilized in other portions of the dragline excavating operation or for other heavy-duty operations.

[0033] The present invention is disclosed above and in the accompanying drawings with reference to a variety of embodiments. The purpose served by the disclosure, however, is to provide an example of the various features and concepts related to the invention, not to limit the scope of the invention. One skilled in the relevant art will recognize that numerous variations and modifications may be made to the embodiments described above without departing from the scope of the present invention, as defined by the appended claims. 

That which is claimed is:
 1. A chain for a mining operation, the chain comprising a plurality of interconnected links that each include a first aperture and a second aperture, a plane of the first aperture being substantially orthogonal to a plane of the second aperture, and each link being formed as a rigid, one-piece member.
 2. The chain recited in claim 1, wherein loops form the first and second apertures, and a connector portion extends between the loops and is integrally-formed with the loops.
 3. The chain recited in claim 2, wherein the connector portion is formed as a single rod member.
 4. The chain recited in claim 1, wherein the links each have a pitch and a cross-sectional dimension, the pitch of each said link being approximately eight times the cross-sectional dimension.
 5. The chain recited in claim 1, wherein the links each have a pitch and a cross-sectional dimension, the pitch of each said link being at least four times the cross-sectional dimension.
 6. A chain for a dragline excavating operation, the chain comprising a plurality of interconnected links, each said link having a first end defined by a first closed loop, a second end defined by a second closed loop, and a central connecting rod interconnecting the first and second loops, the loops and the connecting rod being integrally formed, and a plane of the first loop being non-parallel to a plane of the second loop.
 7. The chain recited in claim 6, wherein the plane of the first loop is generally orthogonal to the plane of the second loop.
 8. The chain recited in claim 6, wherein the links each have a pitch and a cross-sectional dimension, the pitch of each said link being approximately eight times the cross-sectional dimension.
 9. The chain recited in claim 6, wherein the links each have a pitch and a cross-sectional dimension, the pitch of each said link being at least four times the cross-sectional dimension.
 10. A dragline excavating operation comprising: a dragline bucket for receiving excavated material; at least one line for supporting the dragline bucket; and a chain secured to the dragline bucket, the chain including a plurality of interconnected links, each said link having a pair of closed end loops and a connecting portion, each said loop lying generally in a plane, and the planes of the loops being angled relative to each other.
 11. The dragline excavating operation recited in claim 10, wherein the planes of the loops are oriented orthogonally relative to each other.
 12. The dragline excavating operation recited in claim 10, wherein the connecting portion for each said link is a single rod member.
 13. The dragline excavating operation recited in claim 10, wherein the links each have a pitch and a cross-sectional dimension, the pitch of each said link being approximately eight times the cross-sectional dimension.
 14. A chain for heavy-duty operations, the chain comprising a plurality of interconnected links that each include: a first loop that forms a first aperture; a second loop that forms a second aperture, a plane of the first aperture being substantially orthogonal to a plane of the second aperture; and a central connecting rod positioned between the first and second loops, wherein each of the first and second loops and the connecting rod are one-piece members that are integrally-connected with each other to form a rigid, one-piece structure for each link.
 15. The chain recited in claim 14, wherein the links each have a pitch and a cross-sectional dimension, the pitch of each said link being approximately eight times the cross-sectional dimension.
 16. The chain recited in claim 14, wherein the links each have a pitch and a cross-sectional dimension, the pitch of each said link being at least four times the cross-sectional dimension.
 17. A method of operating a dragline excavating operation, the method comprising steps of: securing a first end of a chain to a dragline bucket, the chain having at least one link that defines a first loop and a second loop for receiving loops of adjacent links, a plane of the first loop being oriented orthogonally with respect to a plane of the second loop; after a first side of the first loop becomes worn from engaging the ground, disconnecting the chain from the dragline bucket and rotating the chain 180 degrees about a length thereof, and reconnecting the first end to the dragline bucket to position a second side of the first loop in engagement with the ground; after the second side of the first loop becomes worn from engaging the ground, disconnecting the chain from the dragline bucket, and connecting a second end of the chain to the dragline bucket to position a first side of the second loop in engagement with the ground; and after the first side of the second loop becomes worn from engaging the ground, disconnecting the chain from the dragline bucket and rotating the chain 180 degrees about the length thereof, and reconnecting the second end to the dragline bucket to position a second side of the second loop in engagement with the ground.
 18. A method of excavating comprising: supporting a dragline bucket by at least one hoist line; coupling a chain to the dragline bucket, the chain including a plurality of interconnected links, each link including a first aperture and a second aperture, wherein a plane of the first aperture is substantially orthogonal to a plane of the second aperture; and operatively connecting the chain to a drag mechanism and operating the drag mechanism to pull the dragline bucket along the ground via the chain. 